<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <!-- 样式 -->
    <style>
        button {
            background-color: blue;
            font-size: 24px;
        }
    </style>
</head>
<body>
    <!-- 结构 -->
    <button>许个愿吧</button>
    <!-- 行为 -->
    <script>
        document.querySelector('button').onclick = () => {
            alert('有钱有闲')
        }
    </script>
</body>
</html>